Switch to an enum and tidy up the documentation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

All modern drivers can support extra partitions using the extended
dev_t.  In fact except for the ioctl method drivers never even see
partitions in normal operation.

So remove the GENHD_FL_EXT_DEVT and allow extra partitions for all
block devices that do support partitions, and require those that
do not support partitions to explicit disallow them using
GENHD_FL_NO_PART.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This flag is not set directly anywhere and only inherited from
GENHD_FL_HIDDEN.  Just check for GENHD_FL_HIDDEN instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The GENHD_FL_NO_PART_SCAN controls more than just partitions canning,
so rename it to GENHD_FL_NO_PART.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20211122130625.1136848-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

GENHD_FL_CD marks a gendisk as a vaguely CD-ROM like device.
Besides being used internally inside of sunvdc.c an xen-blkfront it
is used by xen-blkback as a hint to claim a device exported to a
guest is a CD-ROM like device.  Just check for disk->cdi instead
which is the right indicator for "real" CD-ROM or DVD drivers.  This
will miss the paravirtualized guest drivers, but those make little
sense to report anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE is all about the event reporting
mechanism, so move it to the event_flags field.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The flag to indicate an unlocked native capacity is dynamic state,
not a driver capability flag, so move it to disk->state.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Now that we have done a spring cleaning on all drivers and added
error checking / handling, let's keep it that way and ensure
no new drivers fail to stick with it.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20211110002949.999380-1-mcgrof@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull more bdev size updates from Jens Axboe:
 "Two followup changes for the bdev-size series from this merge window:

   - Add loff_t cast to bdev_nr_bytes() (Christoph)

   - Use bdev_nr_bytes() consistently for the block parts at least (me)"

* tag 'for-5.16/bdev-size-2021-11-09' of git://git.kernel.dk/linux-block:
  block: use new bdev_nr_bytes() helper for blkdev_{read,write}_iter()
  block: add a loff_t cast to bdev_nr_bytes

Not really needed as both loff_t and sector_t are always 64-bits wide,
but this documents the different types a bit better.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211104172037.531803-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>